Before you start

An SSN or ITIN
Form W-4 with your employer for federal withholding
Form CT-W4 with your employer for Connecticut withholding
Records of foreign income and foreign financial accounts

Step-by-step

1
Complete the W-4 and Connecticut's CT-W4 on day one
Connecticut has its own withholding certificate, and it works differently from the federal form — it asks you to select a withholding code by filing status and expected income rather than to claim allowances. Copying your federal answers across produces the wrong result, and Connecticut's phase-out structures mean the error compounds at higher incomes.
Via employerWho: YouFirst week of employment
2
Understand the 2024 rate cut and where you sit
From 1 January 2024 the two lowest brackets fell from 3% to 2% and from 5% to 4.5%, with the benefit tapering out at higher incomes. The seven brackets top out at 6.99%. If you are reading a guide written before 2024 the bottom of the schedule is wrong. The cut is worth real money to middle incomes and nothing at all at the top.
OnlineWho: You
3
Register the car with the town and expect an annual bill
Connecticut assesses property on a grand list dated 1 October, and vehicles are on it. From the October 2024 list the value comes from the manufacturer's suggested retail price against a statutory depreciation schedule, assessed at 70% and taxed at up to 32.46 mills. The bill comes from the town, not the state, and where the car was garaged on 1 October decides which town.
In personWho: YouAnnual, against the 1 October grand list
4
Price the conveyance tax before you buy a house
Connecticut levies a real estate conveyance tax in two parts — a state tax that steps up with the sale price and a municipal tax with a base rate of 0.25%, which a defined set of eligible municipalities including Hartford may double to 0.5%. The seller pays it. Confirm the current state bands and your town's actual municipal rate with the Department of Revenue Services and the town clerk before you model a sale, because both halves change by legislation.
OnlineWho: You
5
Determine your US tax residency
The substantial presence test counts weighted days across three years to decide whether the US taxes your worldwide income or only US-source income. Certain students and scholars are exempt from counting days for a period, which matters at Trinity, UConn and UConn Health. Your visa category does not settle this.
OnlineWho: You
6
File federal and Connecticut returns, and an FBAR if you need one
The tax year is the calendar year and both returns are due in April. Connecticut's return begins from federal adjusted gross income, so a federal tax treaty position generally flows through. Separately, aggregate foreign financial account balances above USD 10,000 at any point in the year trigger a FinCEN FBAR filing.
OnlineWho: YouApril annually

Documents you’ll need

Form W-2 from each employer, issued by 31 January
Form 1099s for freelance, interest and investment income
Form CT-W4 filed with your employer
Passport and travel history for the substantial presence day count
Foreign account statements for FBAR reporting

Things most newcomers don’t know

Connecticut cut its bottom two income tax rates in 2024, and most write-ups are stale.

With effect from 1 January 2024 the 3% bracket became 2% and the 5% bracket became 4.5%, with the benefit phased out at higher incomes and the top rate unchanged at 6.99%. Anything written before that describes a schedule that no longer exists at the bottom. For a middle income this is a real annual difference, and it is the sort of change that a relocation article from 2022 will quietly get wrong.

Source: Connecticut Department of Revenue Services

No Connecticut town levies an income tax — the whole local burden is property.

Ohio and Michigan cities tax where you work, Indiana counties tax where you live, and New York City and Yonkers tax residents. Connecticut allows none of it. What towns do instead is set a mill rate on property, and because there is no county layer either, that single rate carries schools, police, roads and everything else. It is why the mill rate is such a live topic here and why the town line matters more than in almost any other state.

Source: Connecticut Office of Policy and Management

The car tax follows the 1 October grand list, not your current address.

A vehicle garaged in Hartford on 1 October is on Hartford's list for that assessment year even if you move to Glastonbury in November. Newcomers get a bill from a town they have left and assume it is an error. It usually is not — but there are procedures where a vehicle was sold or moved out of state, so read the assessor's guidance rather than binning the bill.

Source: Connecticut Office of Policy and Management

Hartford is one of the towns allowed to charge double the base municipal conveyance tax.

Connecticut's conveyance tax has a state part and a municipal part. The base municipal rate is 0.25%, and a defined set of eligible municipalities — Hartford among them — may levy up to 0.5%. That is a seller's cost rather than a buyer's, but it belongs in the sums on either side of a Hartford sale, and the eligible list and the state bands are both set by legislation that changes. Confirm the current position with DRS and the town clerk rather than with an older article.

Source: Connecticut Department of Revenue Services — real estate conveyance tax

Common mistakes to avoid

Using pre-2024 rate tables — Connecticut's two lowest brackets were cut with effect from 1 January 2024.
Copying federal W-4 answers onto Connecticut's CT-W4, which uses withholding codes rather than allowances.
Ignoring a car tax bill from a town you have moved away from.
Comparing house prices between towns without comparing mill rates.
Assuming an older write-up's conveyance tax figures still hold — both the state bands and the municipal rates are set by legislation.

Some of this may be out of date. Spotted something inaccurate? Help us keep it right for the next newcomer.